Nontraumatic leaks primarily occur in adults > 30 yrs. Often insidious. May be mistaken for allergic rhinitis. Unlike traumatic leaks, these tend to be intermittent, the sense of smell is usually preserved, and pneumocephalus is uncommon ¹⁾.

Spontaneous Cerebrospinal fluid fistulas are most commonly located along the anterior skull base. Sphenoidal localization is less common and, among these, clival localization is even rarer.

They represent a surgical challenge because of their high recurrence rates. The most important factor for obtaining a successful repair in these patients is reducing their intracranial pressure through nutritional, medical or surgical means ²⁾.

Sometimes associated with the following ³⁾:

1. agenesis of the floor of the anterior fossa (cribriform plate) or middle fossa

2. empty sella syndrome: primary or post-transsphenoidal surgery

3. increased ICP and/or hydrocephalus

4. infection of the paranasal sinuses

5. tumor: including pituitary neuroendocrine tumors, meningiomas

6. a persistent remnant of the craniopharyngeal canal ⁴⁾

7. AVM ⁵⁾.

8. congenital anomalies: most involve dehiscence of bone

a) dehiscence of the foot plate of the stapes (a congenital abnormality) which can produce CSF rhinorrhea via the eustachian tube ⁶⁾.

b) dehiscence below foramen rotundum.

Spontaneous posterior fossa cerebrospinal fluid fistula

67 patients with a spontaneous leak between 2005 and 2014, retrospective data analysis was performed on six patients with clival localization of the defect. Three patients received a skull base repair with a multilayered reconstruction, and three patients underwent a single-layered reconstruction using a pedicled nasoseptal flap.

The patient cohort included six women with a mean age of 60 (36-91 years old). The mean length of the follow-up was 69.5 months (22-114 months). The overall success rate of the primary endoscopic repair was 83.3% (five out of six), this increased to 100% after revision surgery.

This series, though numerically limited, suggests that a minimally invasive endoscopic repair of idiopathic clival leaks may be accomplished with an acceptable rate of morbidity and excellent outcomes. Moreover, nowadays the pedicled nasoseptal flap has been confirmed to be the “workhorse” for the reconstruction of clival defects ⁷⁾.

Eight patients were managed via an endoscopic approach and one patient through an intracranial approach. The MRI/T2-FLAIR test was used for localization of the site of the leak. The test confirmed the site of Cerebrospinal fluid fistula in 6 patients. Successful repair of CSF rhinorrhea was achieved in 7 of 8 patients with a single endoscopic procedure; one patient required two procedures after a re-leak 18 months following the first repair.

Non-traumatic CSF rhinorrhea is a relatively rare condition and occurs secondary to different etiologies. Among multiple techniques available for localization, MRI/FLAIR is effective but requires further evaluation and polishing. In the absence of a large skull base lesion or tumor, endoscopic repair of CSF fistula carries a high success rate with a high margin of safety and low morbidity rate ⁸⁾.

Cruz et al., report the case of a 28-year-old woman with a spontaneous Cerebrospinal fluid fistula from the sleeve of a redundant thoracic nerve root. She presented with postural headaches and orthostatic symptoms indicative of intracranial hypotension. CT myelography revealed that the lesion was located at the T-11 nerve root. After failure of conservative management, including blood patches and thrombin glue injections, the patient was successfully treated with surgical decompression and ligation of the duplicate nerve, resulting in full resolution of her orthostatic symptoms ⁹⁾.